From the paper: (1) Statistics obtained from Hardmanet al.(2019) (2) Statistics obtained from Blanco et al.(2016) (3) Statistics obtained from Transportation R

From the paper: (1) Statistics obtained from Hardmanet al.(2019) (2) Statistics obtained from Blanco et al.(2016) (3) Statistics obtained from Transportation Research Board of the National Academy of Sciences (2013) I don't understand how such chronologically disparate sets of data could produce reliable statistics. The Telsa demographic data (1) was from a "2018 demographic survey of 424 Tesla owners"